DESCRIPTION:(provided by applicant)Control of voluntary movements plays an integral role in nearly every human behavior. The ultimate goal of this research is to understand the role of the motor cortex in controlling movement using exploratory, rhythmic whisking as a model system. Specifically, we propose a coordinated series of electrophysiological and neuroanatomical experiments to address the mechanisms of cortical and subcortical influences on the facial motoneurons that control whisking behavior ("whisking motoneurons"). Whisking motoneurons are located in the lateral facial nucleus which does not receive direct input from the motor cortex. Based on previous studies and preliminary evidence from our laboratory, we propose that a pathway exists by which the whisker motor cortex directly innervates pre-motoneurons located in the parvocellular reticular formation, and these pre-motoneurons project to and regulate the rhythmic activity of whisking motoneurons. The Specific Aims addressed in this proposal will test the following hypotheses: 1) Intrinsically bursting premotoneurons located in the parvocellular reticular formation project directly to and regulate the rhythmic activity of whisking motoneurons, 2) Regions that project to and evoke repetitive firing in whisking motoneurons also project to motoneurons that control other rhythmic motor activities, 3) Activity of pre-motoneurons is causally related to exploratory, rhythmic whisking as assessed by recording from pre-motoneurons in awake, behaving rats.